Hydraulic uniflow control unit

ABSTRACT

There is disclosed a hydraulic control unit particularly for use in steering apparatus for boats, and in which the hydraulic fluid always flows in the same direction. The unit has pressure passages having ends to be connected to opposite sides of a pumping unit and opposite ends to be connected to the device to be controlled, such as the opposite ends of a slave cylinder which operates the rudder of a boat. A shuttle valve normally closes off the pressure passages and shuts them off from a common return passage which is connected to the reservoir of the pumping unit. When hydraulic fluid flows through one pressure passage, it shifts the shuttle valve to open the passage and connect the other passage to the return passage. The flowing fluid also passes through a check valve in the pressure passage and shifts a lock spool to open a corresponding check valve in the other pressure passage.

United States Patent [72] lnventors Ray A. R. Wood;

Robert A. Atkins, Vancouver, British Columbia, Canada [2]] Appl. No.875,030 [22] Filed Nov. 10, 1969 [45] Patented Apr. 27, 1971 {73]Assignee Capilano Engineering Co. Ltd.

Vancouver, British Columbia, Canada [54] HYDRAULIC UNIFLOW CONTROL UNIT4 Claims, 6 Drawing Figs.

[52] 11.8. C1 137/102, 91/420 [51] lnt.Cl F1511 11/08 [50] Field ofSearch 137/87, 102; 91/420 [56] References Cited UNITED STATES PATENTS2,648,346 8/1953 Deardorffet a1. 137/102 2,720,755 10/1955 Gardiner91/420X Primary ExaminerLaverne D. Geiger Assistant Examiner-David JZobkiw V Attorney-Fetherstonhaugh and Co.

CT: There is disclosed a hydraulic control unit particularly for use insteering apparatus for boats, and in which the hydraulic fluid alwaysflows in the same direction. The unit has pressure passages having endsto be connected to opposite sides of a pumping unit and opposite ends tobe connected to the device to be controlled, such as the opposite endsof a slave cylinder which operates the rudder of a boat. A shuttle valvenormally closes otT the pressure passages and shuts them off from acommon return passage which is connected to the reservoir of the pumpingunit. When hydraulic fluid flows through one pressure passage, it shiftsthe shuttle valve to open the passage and connect the other passage tothe return passage. The flowing fluid also passes through a check valvein the pressure passage and shifts a lock spool to open a correspondingcheck valve in the other pressure passage.

HYDRAULIC UNIFIDW CONTROL UNIT BACKGROUND OF THE INVENTION Thisinvention relates to hydraulic uniflow control units which may be usedfor different purposes, but which are primarily designed to be used inthe steering control apparatus of a boat which includes one or moresteering pump units and a slave cylinder for controlling the rudder ofthe boat.

It is desirable to be able to steer many different types of boats fromvarious stations therein. Hydraulic steering systems are usually usedfor this purpose, and in the past, it has been difiicult to get air outof the systems and to keep it out, to locate check valves that are notoperating properly because of dirt of other obstructions, and to preventloss of control when two helms are simultaneously operated in oppositedirections.

One of the hydraulic control systems in common use has check valves forthe pressure lines at each steering pump unit. If dirt gets into any oneof these valves, it prevents the slave cylinder from being locked tohold the rudder in the desired position or setting. When this happens,it is difficult and time consuming to locate the valve that needs to becleaned. Another difficulty results from the fact that the hydraulicfluid flows back and forth through each pressure line between the pumpsand the slave cylinder so that it is very difficult to purge the linesof air. When air is trapped in the lines, the system becomes soft andunresponsive. Thus, a long time consuming operation is needed at thetime of installation in order to purge the air. As the piston of theslave cylinder is connected to the rudder througha piston rod whichextends through one end of the cylinder, it is necessary to provide acompensating rod from the piston to the opposite end of the cylinder inorder to be sure that exactly the same amount of oil returns to thesteering pump as is pumped by the latter. This necessitates extra sealsat the opposite end of the cylinder. Another dangerous problem with thepast control systems results from the fact that if two steering unitsare simultaneously rotated in opposite directions, control of the vesselis lost as the fluid circulates freely between the two steering units,leaving the slave cylinder unlocked. Furthermore, in the prior systemsit is necessary to provide a continuous substantial rise in the pipingfrom the slave cylinder to all of the steering units in order to try toprevent air from being trapped therein.

SUMMARY OF THE INVENTION The hydraulic uniflow control units of thisinvention eliminate the difficulties pointed out above. Each uniflowcontrol unit includes two check valves which eliminate the necessity ofcheck valves in the pressure lines at each of the steering units. Thisnot only reduces the cost, but if a check valve is held open by dirt,the trouble can be in only one place and therefore it is easy to locateand remedy it. The control system is very easy to purge free of air asthe hydraulic fluid always travels in the same direction. Therefore, thesystem can be purged quickly and easily merely by turning each steeringunit the full distance back and forth several times. This saves timewhen the equipment is installed, the system is always positive acting,and no expensive and complicated bleeding devices are required. As itdoes not matter whether the same amount of fluid is moved out of theslave cylinder as is pumped thereinto, no compensating shaft with itsaccompanying seals is required for the slave cylinder. This reducescost, and it eliminates another possible source of leakage. If twosteering units are simultaneously rotated in opposite directions, theone with the most force applied will operate, while the other will not.Therefore, there is no loss of control of the vessel when this occurs.The unidirectional flow of the fluid eliminates the necessity of havingall of the lines upwardly inclined.

A hydraulic uniflow control unit according to the present inventionincludes first and second pressure passages having inlet ends to beconnected to opposite sides of a reversible pump unit and outlet ends tobe connected to opposite ends of a slave cylinder. A common returnpassage is connected to both pressure passages. A shuttle valve normallycloses off both pressure passages and closes off the return passage fromboth pressure passages to prevent fluid from flowing through any of saidpassages. The shuttle valve is positioned to be moved by fluid flowingthrough the first pressure passage to permit said flow and to permitfluid to flow from the second passage outlet end to the return passageand vice versa. There is a check valve in each pressure passage normallypreventing fluid from flowing therein from its outlet end to its inletend. A lock spool is positioned to unseat the check valve of the secondpressure passage when fluid flows through the first pressure passage,and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I diagrammatically illustrates auniflow control unit of this invention in use in a vessel steeringsystem having three steering pump units and a slave cylinder controllingthe rudder of the vessel,

FIG. 2 is a diagrammatical sectional view taken on the line 2-2 of FIG.1,

FIG. 3 is a perspective view of the uniflow control unit,

FIG. 4 is a vertical section through the unit taken on the line M ofFIG. 3, showing the unit in the locking position, and

FIGS. 5 and 6 are views similar to FIG. 4, but showing the unit set forturns to the left and to the right, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2 ofthe drawings, 10 is a hydraulic uniflow control unit in accordance withthis invention which is operatively connected to a slave or operatingcylinder II which, in turn, controls a rudder 12 of a vessel 13 in whichthe apparatus is located. Cylinder II has a piston 15 therein, and a rod16 connected to this piston extends through suitable seals, not shown,in an end of the cylinder to an arm 17 which is connected to the rudderpost 18. Movement of piston 15 back and forth in cylinder II movesrudder 12 to steer the vessel. Control unit 10 is connected by pressurelines 22 and 23 to the opposite ends of cylinder [1.

Vessel I3 is provided with one or more steering pump units 26, therebeing three of these units shown in FIG. 1. Each steering unit 26 can beany known unit for this purpose, each one having a reversible pump whichis operated by a steering wheel 28. Each steering unit has a reservoirfor the hydraulic fluid of the system. The opposite sides of each pumpunit are connected by pressure lines 30, 31 and 32, 33 to the controlunit 10. A return line 35 connects control unit 10 to the bottom of thereservoir of one of the steering units 26, while another return line 36connects the top of said reservoir to the bottom of the reservoir of thenext steering unit, and another return line 37 connects the top of thelatter reservoir to the bottom of the reservoir of the next steeringunit. In other words, there is a return line from control unit 10 to thebottom of the reservoir of the first steering unit of a series of theseunits, while the top of the reservoir of each successive steering unitis connected to the bottom of the reservoir of the following unit. Thelines of this system do not have to be inclined upwardly. The top of thereservoir of the last steering unit 26 is open to atmosphere, such as bymeans of a pipe 38. The entire system may be filled with hydraulic fluidthrough this pipe 38. The pressure pumps of the steering units 26 areconnected in parallel to pressure ports of control unit 10, while thereservoirs of these steering units are connected in series with a returnport of the control unit.

FIGS. 3 and 6 illustrate control unit 10 in detail. This unit includes abody 45. This body has pressure ports 48 and 49 and a return port 50opening out from one edge thereof, and lines 31, 33 and 35 are connectedto body 45 so as to register with ports 48, 49 and 50, respectively.Body 45 also has outlet ports 51 and 52 opening out from an oppositeedge thereof and communicating with control lines: 22 and 23,respectively.

A pair of substantially horizontal bores 55 and 56 extend through body45, the ends of bore 55 being closed by plugs 58 and 59, and the ends ofbore 56 being closed by fittings 61 and 62. Pressure passages 65 and 66are formed in the control unit body, passage 65 having an outlet end atpressure port 48 and an outlet end at outlet port 51, while passage 66has an inlet end at pressure port 49 and an outlet end at outlet port52. Pressure passage 65 is made up of an inlet section 60 extending fromport 46 to bore 55, part of said bore, two parallel intennediatebranches 6i and 62 extending from bore 55 to another section 63 whichextends to bore 56, part of the latter bore, and outlet section 64 whichextends from this bore to outlet port 51. Pressure passage 66 is similarto passage 65, and is made up of an inlet section 67, two substantiallyparallel intermediate branches 68 and 69, another section 70, and anoutlet section 71.

A check valve is located in pressure passage 65 and consists of a ball74 normally pressed onto a seat 75 in bore 56 by a spring 76. Anothercheck valve is provided in pressure passage 66, said valve consisting ofa ball 78 normally resting on a seat 7? in bore 56 and retained on saidseat by a spring 30.

Return passage means is provided in body 45 and in this example consistsof a return pamge 83 extending inwardly of the body from return port 56to bore 55.

A shuttle valve 36 is slidably mounted in bore 55 and has an end section88 normally closing branches 61 and 62 of pressure passage 65, and anend section 89 normally closing branches 68 and 69 of pressure passage66. when the shuttle valve is in the position shown in FIG. 4, no fluidcan flow through either of the pressure passages 65 or 66, or fromeither of said passages to return passage $3.

A lock spool 91 is slidably mounted in bore 56 substantially midwaybetween the ends thereof. Pins 92 and 93 project from opposite ends ofspool 91 towards check valves 74 and 78, but these pins are of suchlength that the balls nonnally remain on their respective seats.

FIG. 4 shows the various components of control unit 10 in their neutralpositions, at which time, check balls 74 and 78 prevent fluid frommoving through lines 22 and 2.3 from the opposite ends of slave cylinderll so that rudder 12 is locked in its position. When one of the steeringunits 26 is operated by its wheel 28, to turn vessel 15 in onedirection, for example, to port or to the left, hydraulic fluid ispumped through lines 32 and 31 into pressure passage 65. This shiftsshuttle valve 86 to the right, as shown in FIG. 5, to uncover branches61 and 69 of pressure passages 65 and 66. Branch 62 is still shutofffrom return passage 63 by shuttle section 88, and shuttle section 89keeps branch 68 of passage 66 closed while the latter passage is incommunication with return passage 83 through branch 69. The pressurefluid travels through passage 65, unseating check ball 76, and flowingthrough line 22 to one end of slave cylinder ll to turn the rudder. Atthe same time, the pressure fluid shifts lock spool 91 to the right sothat pin 93 unseats check ball 78, allowing fluid to flow from theopposite end of the slave cylinder through line 23, part of pressurepassage 66, return passage 83 and thence through line 35 to the fluidreservoir of the steering unit 26 to which said line is connected.

FIG. 6 illustrates the position of the various components of controlunit 10 when the steering wheel of one of the pump units 26 is rotatedin the opposite direction to turn the vessel to starboard or to theright. At this time, pressure fluid flowing along pressure passage 66shifts shuttle valve 86 and lock spool 91 to the left so that said fluidcan flow through line 23 to the opposite end of the slave cylinder. Atthe same time, check ball 76 is unseated and, therefore, fluid can flowback from the slave cylinder through line 22, a part of pressure passage65, return passage 83, and return pipe 35 to the fluid reservoir of thenearest steering unit.

Check valves 74 and '78 are the only ones necessary to lock the slavecylinder and, consequently, rudder 12 in any set position. Thiseliminates the necessity of check valves for this purpose at each of thesteering units 26. As the hydraulic fluid always flows in the samedirection from the steering pump units through lines 31 and 33 to thecontrol unit, and always flows from said unit in the same directionthrough return line 35, 36 and 37 to the reservoirs of the steeringunits, the lines of the hydraulic system can be quickly and easilypurged of any air therein merely by turning the steering wheels 28 backand forth to the full extent several times, since the fluid is pumpedthrough the pressure lines, the control unit, and the return lines tothe reservoirs of the steering unit which are in communication with eachother so that any air in the lines eventually leaves the system throughpipe 38, even if there is no gradual rise in any line. The slavecylinder ll does not need an extra rod or shaft from piston 15 tocompensate for rod 16 since it does not matter whether the same amountof fluid is directed out of the cylinder as is directed into it. If twoof the steering wheels 28 are rotated in opposite directions at the sametime, the one with the most force applied to it will pump fluid tocontrol unit 10, and this will shift shuttle valve 86,and lock spool 91so as to prevent fluid from being pumped through the control unit by theother steering unit. Thus, the vessel will remain under the control ofthe steering unit to which the most force had been applied, but it willnot be out of control at any time. As a continuous rise is not necessaryfor the pipelines, these can be placed in a convenient place in thevessel.

We claim:

1. A hydraulic uniflow control unit comprising a body, first and secondpressure passages extending through the body and having inlet ends to beconnected to opposite pressure sides of at least one reversible pumpunit and outlet ends to be connected to opposite ends of an operationcylinder, return passage means in the body connected to both of saidpressure passages and to be connected to the return of said pump unit, ashuttle valve slidably mounted in the body and normally shutting both ofsaid pressure passages and closing off the return passage means fromboth of said pressure passages to prevent fluid from flowing throughsaid pressure passages and said passage means, said shuttle valve beingmoved by fluid flowing through the first passage to permit said flow andto permit fluid to flow from the second passage outlet end to the returnpassage means and vice versa, a check valve in each pressure passagenormally preventing fluid from flowing therein from the outlet end tothe inlet end thereof, and a lock spool slidable mounted in the body andpositioned to unseat the check valve of the second passage when fluidflows through the first passage and vice versa.

2. A control unit as claimed in claim 1 in which each pressure passagehas two parallel intermediate branches, one branch of each pressurepassage being in communication with the inlet end of said each pressurepassage and the other of said branches of said each pressure passagebeing in communication with said return passage means, said shuttlevalve has two sections, said sections normally closing off both of thebranches of both of said pressure passages, and when moved by fluid inthe first pressure passage the shuttle valve uncovers the branch whichis in communication with the inlet of the first pressure passage anduncovers the branch of the second pressure passage which is incommunication with said return passage means, and vice versa.

3. A control unit as claimed in claim 2 in which said lock spool has oneend exposed to fluid in the first pressure passage between the twointermediate branches thereof and the check valve therein and anopposite end exposed to fluid in the second pressure passage between thetwo intermediate branches thereof and the check valve therein, andincluding pins on opposite ends of the lock spool and extending towardsadjacent check valve, and when fluid in the first pressure passage flowsagainst the adjacent end of the lock spool, the latter is shifted tocause the pin on its opposite end to open the check valve in the secondpressure passage and vice versa.

41. A control unit as claimed in claim 1 in which said lock spool hasone end exposed to fluid in the first pressure passage between the inletend thereof and the check valve therein and an opposite end exposed tofluid in the second pressure passage between the inlet end thereof andthe check valve the lock spool, the latter is shifted to cause the pinon its opposite end to open the check valve in the second pressurepassage and vice versa.

1. A hydraulic uniflow control unit comprising a body, first and secondpressure passages extending through the body and having inlet ends to beconnected to opposite pressure sides of at least one reversible pumpunit and outlet ends to be connected to opposite ends of an operationcylinder, return passage means in the body connected to both of saidpressure passages and to be Connected to the return of said pump unit, ashuttle valve slidably mounted in the body and normally shutting both ofsaid pressure passages and closing off the return passage means fromboth of said pressure passages to prevent fluid from flowing throughsaid pressure passages and said passage means, said shuttle valve beingmoved by fluid flowing through the first passage to permit said flow andto permit fluid to flow from the second passage outlet end to the returnpassage means and vice versa, a check valve in each pressure passagenormally preventing fluid from flowing therein from the outlet end tothe inlet end thereof, and a lock spool slidable mounted in the body andpositioned to unseat the check valve of the second passage when fluidflows through the first passage and vice versa.
 2. A control unit asclaimed in claim 1 in which each pressure passage has two parallelintermediate branches, one branch of each pressure passage being incommunication with the inlet end of said each pressure passage and theother of said branches of said each pressure passage being incommunication with said return passage means, said shuttle valve has twosections, said sections normally closing off both of the branches ofboth of said pressure passages, and when moved by fluid in the firstpressure passage the shuttle valve uncovers the branch which is incommunication with the inlet of the first pressure passage and uncoversthe branch of the second pressure passage which is in communication withsaid return passage means, and vice versa.
 3. A control unit as claimedin claim 2 in which said lock spool has one end exposed to fluid in thefirst pressure passage between the two intermediate branches thereof andthe check valve therein and an opposite end exposed to fluid in thesecond pressure passage between the two intermediate branches thereofand the check valve therein, and including pins on opposite ends of thelock spool and extending towards adjacent check valve, and when fluid inthe first pressure passage flows against the adjacent end of the lockspool, the latter is shifted to cause the pin on its opposite end toopen the check valve in the second pressure passage and vice versa.
 4. Acontrol unit as claimed in claim 1 in which said lock spool has one endexposed to fluid in the first pressure passage between the inlet endthereof and the check valve therein and an opposite end exposed to fluidin the second pressure passage between the inlet end thereof and thecheck valve therein, and including pins on opposite ends of the lockspool and extending towards adjacent check valves, and when fluid in thefirst pressure passage flows against the adjacent end of the lock spool,the latter is shifted to cause the pin on its opposite end to open thecheck valve in the second pressure passage and vice versa.